You are attempting to change your source code while the program (or IntelliJ’s debugger) is still running. This is what the HotSwap feature does according to IntelliJ’s KB. Please make sure your program and/or debugger is stopped before re-launching the program and the issue should be resolved.
You can either use the open-source HotSpot VM or the commercial JRebel IDE plugin to easily achieve your goal (view comparison table here).
A solution that uses devTools works : 1 – Adding devtools to your project <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> </dependency> 2 – Enabling automatic build Open the Settings –> Build-Execution-Deployment –> Compiler and enable : Build Project Automatically. 3 – Update the value of compiler.automake.allow.when.app.running press ctrl+shift+A and search for the registry. In the registry, enable : … Read more
After saving your class while waiting on your breakpoint just recompile your class with Build -> Compile ‘MainTest.java’ or press Ctrl+Shift+F9 with the standard key bindings. IntelliJ IDEA will then show a small dialog in which it asks you if you want to reload that class.
Take a look at DCEVM, it’s a modification of the HotSpot VM that allows unlimited class redefinitions at runtime. You can add/remove fields and methods and change the super types of a class at runtime. The binaries available on the original site are limited to Java 6u25 and to early versions of Java 7. The … Read more